Facts about H1N1 epidemic and vaccine in Australia/ Australian Prescriber

Professor Peter Collignan provides us with facts (finally we get to see some unvarnished information) on how bad the H1N1 virus was for healthy people, as well as learning of much higher adverse event rates for the vaccine than have been previously reported.  However, the CSL vaccines used in Australia were almost certainly different than the vaccines used in the US.  Only one in a million healthy people under age 40 (omitting pregnant women) died.  CDC never broadcast this figure.

In the 2009 Australian winter, swine flu’s associated mortality rate was 0.9 per 100 000 people. In those under 40 years with no risk factors, the mortality rate was less than one per million.  While there were some differences (for example pregnant women), the overall effects of this virus as judged by absenteeism, hospitalisations and deaths were similar to those of previous seasonal influenza strains…

In an Australian H1N1 vaccine trial of adults (aged 18–65 years), 27% had protective antibody concentrations and 62% had detectable pre-existing antibodies…

In Australia, we do not have good postmarketing surveillance mechanisms in place and mainly rely on voluntary reporting. This is unlikely to accurately measure the percentage of people who get adverse effects or to identify rare adverse effects in a timely fashion…

The reason these issues are important is that we do not have robust data on which to make proper decisions on the cost-effectiveness of any mass vaccine programs. In young people without risk factors, the rates of death and complications last winter from swine flu were very low and are similar to the risk of serious vaccine-associated adverse effects such as Guillain-Barré syndrome and anaphylaxis. Around 50% of people who received the H1N1 vaccine in the Australian trial had mild to moderate systemic adverse effects and 1.7% had (solicited) systemic adverse effects recorded as severe.  In children, 20% had moderate to severe systemic adverse effects after receiving a single 15 microgram dose of vaccine.  It is very important that we make sure we do more good than harm with any vaccine.

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